The body of John F. Kennedy Jr has been located in the water off Martha's Vineyard, Massachusetts, NBC News reported, citing officials close to the search.

Kennedy's body was found during the night in about 100 feet of water along with a "significant part of the wreckage" of his single-engine private airplane that crashed last Friday night, NBC said.

"They've got the fuselage and John Kennedy's in it," a high-level government source said. The White House later confirmed his body had been discovered.

There was no immediate word about whether the women's bodies had been located.

Jim Hall, chairman of the National Transportation Safety Board, and Coast Guard Rear Adm. Richard Larrabee, who was overseeing the search, cancelled a round of morning TV appearances and went to the USS Grasp, the ship where the wreckage was to be deposited after being raised from the ocean floor.

The heightened activity took place after ships from the Navy, Coast Guard and National Oceanographic and Atmospheric Administration spent Tuesday night scouring a site 7.5 miles southwest of the Martha's Vineyard coast, a spot that investigators had speculated was the likely splash point for the plane.

It crashed Friday night while carrying JFK Jr, 38, his wife, Carolyn Bessette Kennedy, 33, and her sister, Lauren Bessette, 34. There was no immediate word about whether the women's bodies had been located.

Government sources said Kennedy family aides and friends were in New York, planning a memorial service for all three victims, perhaps on Saturday.

On the fourth full day of the search, the Federal Aviation Authority (FAA) acknowledged it was asked in a phone call from an intern at the Martha's Vineyard airport to help locate the plane on Friday night.

The caller, 21-year-old Adam Budd, expressed no great urgency as he telephoned an FAA station in Bridgeport, Connecticut, at 10.05 pm, FAA officials said.

He said he called at the request of an unidentified couple who had come to the airport to meet Lauren Bessette. JFK Jr and his wife had planned to drop her off on their way to Hyannis Port for his cousin's wedding.

Budd asked if the agency could track the aeroplane, but the person at the FAA station questioned him about who he was and finally said: "We don't give this information out to people over the phone." Budd gave up, saying, "It's not a big deal."

The plane had gone down about 9.40 pm. Nothing was done until a much more urgent call was made to the Coast Guard at 2.15 am by a Kennedy family friend.

An FAA spokesman said the person who took Budd's call acted appropriately. But an unidentified FAA source said in Wednesday's Boston Globe that the agency was considering disciplinary action against the employee for not coming forward about the call when it became clear the plane was missing.